1<8/7<10/7

1<9/7<10/7

PHải là lục bạc + mũ lv 2 = 272

đó là số 9/7 ; 8/7 . chỉ có thế thôi

D

\(1< \dfrac{x}{7}< \dfrac{10}{7}\)

\(1\times7< x< \dfrac{10}{7}\times7\)

\(7< x< 10\) 

Vậy các số thích hợp là: 8,9 

Chọn D 

x/5<4/5

=>x<4

mà x là số tự nhiên khác 0

nên \(x\in\left\{1;2;3\right\}\)

`x/5 < 4/5`

`<=> x < 4`

`<=> x = 1;2;3`

x \(\in\) ( 1,2,3 )

\(a,x< \dfrac{1}{6}:\dfrac{1}{3}=\dfrac{1}{6}\times3=\dfrac{1}{2}=0,5\\ \Rightarrow x=0\\ b,\dfrac{8}{5}>x>\dfrac{6}{7}\\ \Rightarrow x=1\)

C

C

c?

b)\(C=\frac{5x-19}{x-4}=\frac{5x-20+1}{x-4}=\frac{5\left(x-4\right)+1}{x-4}=5+\frac{1}{x-4}\)

Để C đạt giá trị nhỏ nhất => 1/x-5 phải đạt giá trị nhỏ nhất

=> 1/x-5=-1

=>x-5=-1

=>x=4

Giá trị nhỏ nhất của C là : 5 - 1 = 4 <=> x = 4

Khó vãi lìn.Ai mà giải được,toán lớp 6cow màaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa